Digital microscope having a spring-mounted pivotable unit

ABSTRACT

A digital microscope includes a stationary stand body ( 12 ) and a pivot unit ( 14 ) that is mounted on a shaft ( 24 ) of the stand body ( 12 ), pivotably around the longitudinal axis ( 26 ) of the shaft ( 24 ). The pivot unit ( 14 ) includes an image sensing unit for acquiring images of objects to be examined microscopically. The microscope ( 10 ) further has a brake unit ( 22 ) for braking and/or immobilizing the pivot unit ( 14 ), and an actuation element ( 44 ) for releasing the brake unit ( 22 ). Also provided is an elastic element ( 82 ) that, upon pivoting of the pivot unit ( 14 ) out of a predetermined zero position, exerts a return moment (M R ) on the pivot unit ( 14 ), the return moment (M R ) being directed against a tangential moment (M T ) brought about by the weight (G) of the pivot unit ( 14 ).

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority of German patent application number 102014 114 478.3 filed Oct. 6, 2014, the entire disclosure of which isincorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to a digital microscope that encompasses astationary stand body as well as a pivot unit that is mounted on a shaftof the stand body, pivotably around the longitudinal axis of the shaft.The pivot unit furthermore has an image sensing of a for acquiringimages of objects to be examined microscopically. The microscopefurthermore encompasses a brake unit for braking and/or immobilizing thepivot unit, and an actuation element for releasing the brake unit.

BACKGROUND OF THE INVENTION

High-grade digital microscopes encompass a stationary stand body withwhich the microscope is mounted its placement surface, and a unit,pivotable relative to the stand body around a rotation axis, in which,in particular, the image sensing unit of the digital microscope and anobjective system are arranged. The purpose of this pivoting is inparticular to allow the objects to be observed from different viewingangles; this can be advantageous in particular for the assessment ofdepth information.

If the pivot unit is arranged so that the pivot unit is arrangeduprightly above the stage, and the gravity vertical thus extends throughthe rotation axis of the pivot unit, i.e. the longitudinal axis of theshaft, then no torque acts on the pivot unit and the pivot unit wouldremain in its position even without a brake unit. When the pivot unit ispivoted out of that position, however, the weight of the pivot unitproduces a torque, directed around the rotation axis of the pivot unit,whose magnitude increases as the pivot unit is pivoted farther out ofthe perpendicular position, since the tangential component of the weightthat generates the torque becomes that much greater.

In known digital microscopes this torque is absorbed by the brake unit.This has the disadvantage that upon release of the brake unit in orderto modify the position of the pivot unit, this torque must be applied bythe operator. If he or she neglects this, uncontrolled movement of thepivot unit can occur, which can result in damage to the microscope or inproperty damage or personal harm. It furthermore has the disadvantagethat the brake unit must be correspondingly dimensioned so that it canreliably hold the pivot unit in position even at its maximum deflection.This requires sufficiently large and thus space-intensively dimensionedbrake units.

SUMMARY AND ADVANTAGES OF THE INVENTION

An object of the invention is to describe a digital microscope whosepivot unit can be moved in user-friendly fashion and with minimumexpenditure of force.

This object is achieved by a digital microscope having the features ofClaim 1. Advantageous refinements of the invention are described in thedependent claims.

According to the present invention the microscope encompasses an elasticelement that, upon pivoting of the pivot unit out of a predeterminedzero position, exerts a return moment on the pivot unit, the returnmoment being directed against a torque, called the “tangential moment,”brought about by the weight of the pivot unit.

What is achieved thereby is that in the immobilized state, i.e. with thebrake unit arranged in the braked position, the entire torque of thepivot unit does not need to be absorbed by the brake unit, but insteadat least a portion of the torque is also absorbed by the elasticelement. In addition, when the brake system is released, an operatorthereby needs to exert a smaller force in order to pivot the pivot unitthan if the elastic element were not provided, so that simpler operationis possible. The result is in particular to prevent the pivot unit fromundesirably moving in uncontrolled fashion, thus causing property damageor personal harm. Because the brake system thus needs to exert a smallerbraking force it can thus be of smaller dimensions, so that a compactand economical configuration is achieved.

In a preferred embodiment, at least in a portion of the pivot range ofthe pivot unit, the return moment corresponds to 0.8 to 1.2 times thetangential moment.

The elastic element is in particular selected in such a way that overthe entire pivot range, the return moment corresponds to 0.8 to 1.2times the tangential moment.

What is achieved thereby is that at least in a portion of the range, theresultant moment is equal to at most+/−20% of the tangential moment, andthus the force to be applied by the operator or by the brake unit issmall, and the pivot unit is prevented from springing away in bothdirections when the brake unit is released.

The zero position is, in particular, the position in which the opticalaxis of the microscope or the beam path of the microscope is arrangedperpendicularly to the surface of the microscope stage on which theobjects to be examined microscopically can be arranged. In this zeroposition, the zoom of the microscope is also calibrated with respect tothe surface of the microscope stage.

In a preferred embodiment the elastic element is fastened on the standbody so that the latter does not need to be pivoted together with thepivot unit. A particularly simple configuration is achieved thereby. Inan alternative embodiment of the invention the elastic element can alsobe part of the pivot unit and is thus pivoted along with it.

In a particularly preferred embodiment the elastic element is embodiedin the form of a torsion spring. A particularly simple, economical, andstable configuration is thereby achieved.

The torsion spring is in particular arranged in such a way that thelongitudinal axis of the torsion spring coincides with the longitudinalaxis of the shaft. The “longitudinal axis of the torsion spring” isunderstood in particular to mean the longitudinal axis of the cylinderresulting from the turns of the torsion spring. What is achieved therebyis that the torsion spring is always loaded by an amount equal to theangle through which the pivot unit is pivoted. The result thereof is inparticular that upon pivoting of the pivot unit out of the zero positionin both directions, the torsion spring is correspondingly identicallyloaded in each case, and the same return force and thus the samecounter-moment are thus exerted. The counter-moment is, in particular,that moment which is generated by the return force of the torsion springaround the rotation axis of the pivot unit, i.e. the longitudinal axisof the shaft.

“Longitudinal axes” are understood in the context of this Application inparticular as the respective mathematical concept of an axis, i.e. aninfinite straight line. The longitudinal axis is thus, in particular,not restricted to the length of the component.

In a particularly preferred embodiment the stand body encompasses agate, and the pivot unit encompasses a rod that is fixedly connected tothe pivot unit and projects into the gate. The result is to achieve onthe one hand guidance of the pivot unit upon pivoting thereof withrespect to the stand body, and on the other hand a limitation of themaximum possible pivoting of the pivot unit out of the zero position.The gate is, in particular, embodied in such a way that the pivot unitcan be pivoted out of the zero position in two opposite directionswithin a symmetrical pivoting range. In particular, the pivot unit canbe respectively pivoted 60° in both directions out of the zero position,thus yielding, in particular, a pivoting range of 120°. This limitationhas the advantage that the maximum tangential force of the weightproduced at a tilt of 60° in both directions, i.e. that force whichproduces the torque, is approximately linear with respect to the anglethrough which the pivot unit is pivoted, so that an approximatelyuniform component can be applied as a counter-moment by a spring havinga linear characteristic curve.

The gate is preferably embodied in the shape of a circular segment, thecenter point of the circle being located on the rotation axis of thepivot unit, i.e. on the longitudinal axis of the shaft.

It is furthermore advantageous if the torsion spring is arrangedrotatably on a stub shaft or on a shaft, and if the ends of the wire ofthe torsion spring are angled with respect to the actual turns of thetorsion spring in such a way that a gap is constituted between them.Arranged at least in part in this gap are on the one hand the rod guidedin the gate, and on the other hand a projection of the stand housing.

What is achieved thereby is that upon pivoting of the pivot unit out ofthe zero position in a first direction, the first end of the wire of thetorsion spring braces against the projection and the second end of thewire of the torsion spring is entrained by the rod, so that withincreasing pivoting of the pivot unit out of the zero position, thetorsion spring is correspondingly further loaded and a greater returnforce is applied. Conversely, upon pivoting of the pivot unit out of thezero position in a second direction opposite to the first direction, thefirst end of the wire of the torsion spring is entrained by the rodwhereas the second end of the wire of the torsion spring braces againstthe projection. Here as well, the spring is again correspondinglyincreasingly loaded, thus resulting in an increasing return force as afunction of the deflection angle of the pivot unit. A further result ofthis configuration is in particular that the same return force actsrespectively for an identical deflection in the first and in the seconddirection. The above-described configuration furthermore enables simpleassembly, since the spring simply needs to be slid on and does not needto be laboriously fastened.

It is furthermore advantageous if the longitudinal axis of the stubshaft coincides with the longitudinal axis of the shaft on which thepivot unit is mounted, so that a particularly simple configuration isproduced and the force relationships described above are ensured.

In particular, in the zero position the rod does not contact either ofthe two ends of the torsion spring, so that in the zero state it is notloaded and thus does not exert a return force. This is also notnecessary in the zero position, since no torque is in any caseproceeding from the pivot unit.

It is particularly advantageous if the elastic element is in generalunloaded when the pivot unit is arranged in the zero position. Fatigueeffects on the elastic element are, in particular, thereby avoided.

It is particularly advantageous if the elastic element is embodied orarranged in such a way that its return moment that is brought about bythe return force counteracts the tangential moment that is brought aboutby the tangential force that results upon division of the weight of thepivot unit, acting at the center of gravity of the pivot unit, into aradial force directed along the longitudinal axis of the shaft, and thatsame tangential force. The tangential moment is obtained in particularby multiplying the tangential force by the standard distance of thetangential force from the rotation axis. The return moment is preferablyapproximately the same as or greater than the tangential moment forevery orientation of the pivot unit.

According to a simplified model, the weight of the pivot unit can beimagined as a force acting at the center of gravity of the pivot unit.This weight can be divided, at any position of the pivot unit, into atangential force and a radial force that is directed from the center ofgravity to the rotation axis of the pivot unit and that thus generatesno torque around the rotation axis of the pivot axis. This divisionyields a further force (the tangential force) that is correspondinglyorthogonal to the radial force directed with respect to the rotationaxis, and is thus also orthogonal to a connecting line between thecenter of gravity and the rotation axis of the pivot unit. Thistangential force is responsible for generating the tangential moment.The return force produces the return moment that is directed against thetangential moment, i.e. has an opposite rotation direction.

The return moment is greater than or equal to the tangential moment atleast in a portion of the pivoting range, preferably over the entirepivoting range. This makes possible a particularly simple pivotingmotion of the pivot unit, in which the user can always reliably andaccurately control the pivot unit without a great exertion of force.

The return moment is obtained in particular as the product of the returnforce of the elastic element and the distance of the return force fromthe rotation axis. The tangential moment is correspondingly obtained, inparticular, as the product of the tangential force and the distance ofthe tangential force from the rotation axis.

The return moment (M_(R)) and the tangential moment (M_(T)) inparticular satisfy, at least in a portion of the pivoting range, theequation:M_(R)>=M_(T)

It is particularly advantageous if this equation is satisfied for anypivoting of the pivot unit out of the zero position through at least83%, preferably at least 67%, in particular at least 50% of the maximumpivot angle. The equation is thus satisfied, in particular, at therespective ends of the pivoting range, i.e. for a pivoting operationbetween 83% and 100% or between 67% and 100% or between 50% and 100% ofthe maximum pivot angle. Severe impact against the stops in order tolimit the pivoting range is thereby avoided.

In a particularly preferred embodiment this equation is satisfied forthe entire pivoting range.

It is particularly advantageous if this equation is satisfied for anypivoting of the pivot unit out of the zero position through at least50°, preferably at least 40°, in particular at least 30°. In aparticularly preferred embodiment this equation is satisfied for theentire pivoting range.

In the context of a maximum pivot angle of 60°, the aforementionedequation is thus satisfied in particular for a pivoting operationbetween 50° and 60° or between 40° and 60° or between 30° and 60° out ofthe zero position.

This can be achieved in particular, in the context of a deflection of atmost 60° in each direction viewed from the zero position, by an elasticelement having a linear characteristic curve, since although thetangential moment is proportional to the sine of the pivot angle, thelatter is nevertheless approximately linear in a range of 60° around thezero point.

It is additionally advantageous if the pivot unit encompasses a firstlatching element and if the stand body encompasses a second latchingelement embodied in particular complementarily to the first latchingelement. The first latching element and the second latching element arecoupled to one another when the pivot unit is arranged in apredetermined zero position and when the actuation element is arrangedin an unactuated default position. The first latching element and thesecond latching element are furthermore coupled to one another when thepivot unit is arranged in the zero position and when the actuationelement is actuated within a predetermined first actuation range. Inparticular, the first latching element latches into the second latchingelement.

The result of the coupling of the first and the second latching elementis that an operator of the microscope can easily return to the zeroposition at any time. In particular, if the pivot unit has previouslybeen moved out of the zero position and if the actuation element hasbeen actuated within the first actuation range, the operator can movesaid unit until a latching of the first latching element into the secondlatching element occurs. The latching signals directly and intuitivelyto the operator that the pivot unit is arranged in the zero position.

The zero position is, in particular, selected in such a way that thepivot unit can be pivoted, proceeding from the zero position, throughthe same angle in both directions, so that the zero position representsthe center position.

The brake unit is arranged, in particular, inside the pivot unit, sothat the brake unit is concurrently pivoted.

It is particularly advantageous that, when the pivot unit is arranged inthe zero position and when the actuation element is actuated within apredetermined second actuation range that is different from the firstactuation range and also does not overlap it, the first latching elementis nevertheless not coupled to the second latching element, inparticular does not latch into it. What is achieved thereby is that theoperator can select, as a function of how far he or she actuates theactuation element, whether a coupling of the latching elements is or isnot to occur upon movement into the zero position. This second actuationrange ensures in particular that the pivot unit can be moved from theone side, through the zero position, to the other side without couplingoccurring. This is very useful in particular in a context of videoimaging via the image sensing unit, since otherwise vibrations andshocks could occur due to the latching. In addition, coupling as a ruleintuitively causes operators to modify the force exerted in this region,and thus the rate at which the pivot unit is moved by them, which wouldlikewise produce irregularities in video images.

The first actuation range is arranged in particular between the defaultposition and the second actuation range. It is furthermore advantageousif the first actuation range directly adjoins the default position andif the second actuation range directly adjoins the first actuationrange.

In particular, the brake unit is also released to different extentsdepending on the actuation of the actuation element, i.e. the brakingforce that is generated can be steplessly adjusted depending on how farthe actuation element is actuated. The result is that, thanks to thedefinition of two actuation ranges and not just individual actuationpoints, the braking force can be respectively regulated within theactuation ranges.

Within the first actuation range the brake unit does, in particular,exert a braking force, but it is only of such magnitude that adjustmentof the pivot unit is nevertheless still possible. Conversely, if theactuation element is in its default position, i.e. is unactuated, thebraking force is then so strong that pivoting of the pivot unit is notpossible.

The actuation element can, in particular, be actuated over apredetermined maximum actuation travel. The two actuation ranges are, inparticular, selected in such a way that the first actuation range coversapproximately the first half, adjacent to the default position, of themaximum actuation travel, and the second actuation range covers thesecond half, adjacent to the first half, of the maximum actuationtravel.

The result of this is that sufficient latitude is available for both thefirst and the second actuation range, and that simple and intuitiveoperation by the operator is achieved.

The transition between the two actuation ranges can, in particular, besmooth.

It is furthermore advantageous if, upon an actuation of the actuationelement both within the first actuation range and within the secondactuation range, the brake unit is released at least sufficiently farthat pivoting of the pivot unit is possible.

The latched connection between the first and the second latching elementis, in particular, embodied in such a way that the latched connectionautomatically releases upon pivoting of the pivot unit out of the zeroposition, and/or conversely is automatically established upon pivotingof the pivot unit from a position outside the zero position into thezero position, provided the actuation element is respectively actuatedwithin the first actuation range. What is achieved by way of thisautomatic release and establishment of the latched connection is that noaction is necessary therefor, but instead it occurs automatically uponpivoting of the pivot unit, respectively upon movement into and movementout of the zero position. The latched connection is thus intended not toproduce an immobilizing effect, but merely to produce a positionindication.

The latched connection is embodied in particular in such a way that uponrelease and re-establishment of the latched connection by pivoting ofthe pivot unit, an acoustic, haptic, and/or optical signal, inparticular a “click,” is outputted. The operator can thereby very easilyand intuitively perceive the zero position. This signal is embodied inparticular in such a way that no electrical components are necessarytherefor, but instead it is outputted purely by the mechanicalestablishment of the latched connection.

The latched connection is embodied in particular in the form of aso-called “click stop” that indicates the zero position by way of acorresponding “click.”

In a particularly preferred embodiment the first latching element isarranged movably, in particular linearly displaceably, along apredetermined path. When the actuation element is arranged in itsdefault position, i.e. when the actuation element is not actuated, thefirst latching element is arranged in an initial position in which itengages into the second latching element if the pivot unit is arrangedin the zero position. The latching element is furthermore embodied,and/or coupled to the actuation element, in such a way that upon anactuation of the actuation element within the first actuation range, thefirst latching element is moved at most sufficiently far out of itsinitial position that it latches at least partly into the secondlatching element, always assuming that the pivot unit is arranged in thezero position. It is particularly advantageous if the coupling isaccomplished purely mechanically, so that adjustment is possible evenwithout electrical power. It is furthermore particularly advantageousif, upon an actuation of the actuation element within the firstactuation range, the first latching element remains entirely in itsinitial position so that the latched connection is always established.

Conversely, upon an actuation of the actuation range within the secondactuation range, the first latching element is moved sufficiently farout of its initial position that it no longer latches into the secondlatching element even when the pivot unit is arranged in the zeroposition.

It is thereby easy to ensure that latching occurs only upon an actuationwithin the first actuation range, and depending on the actuation it isthus possible to select whether the zero position is to be “overridden”or a signal is to be outputted.

It is particularly advantageous if the first latching element is biasedinto the initial position via an elastic element. What is achievedthereby is that it always automatically moves back into the initialposition. A further result achieved thereby is that if the latchingelement was not previously arranged in the initial position (for examplebecause the pivot unit is not arranged in the zero position), it isautomatically moved into that initial position. If the pivot unit isarranged outside the zero position, the first latching element is thenmoved out of the initial position, in particular against the returnforce of the elastic element, thanks to contact with an abutmentsurface. If the pivot unit is moved into the zero position, so that thefirst latching element travels into the vicinity of the second latchingelement, it is then moved by the return force of the elastic elementinto that second latching element, and thus into the initial position.Conversely and correspondingly, upon movement of the pivot unit out ofthe zero position in a context of actuation of the first actuationelement within the first actuation element range, the first latchingelement is moved out of the initial position again, against the returnforce of the spring, by way of contact with the second latching elementand/or with the abutment surface.

The elastic element is, in particular, a spring, for example acompression spring. A particularly simple configuration is therebyachieved.

The first latching element is embodied in particular as a pin. Thesecond latching element is correspondingly embodied complementarily as arecess, in particular as a recess within a disk arranged coaxially withthe shaft. If the actuation element is not actuated, or is actuated onlywithin the first actuation range, the pin then latches into the recessif the pivot unit is arranged in the zero position. The pin has, inparticular, a rounded, in particular a semi-spherical end with which itengages into the recess. The recess correspondingly also has, inparticular, a beveled, rounded, or semi-spherical shape. What isachieved thereby is that upon movement of the pivot unit out of the zeroposition, the first latching element is moved by this beveling out ofits initial position. Jamming and a blocking effect of the latchedconnection are, in particular, thereby avoided. Preferably this bevelingor rounding ensures that what is accomplished by the latched connectionis not immobilization but instead only signaling of the zero position.

It is particularly advantageous if the pin comprises an elongated holeinto which a further pin, fixedly connected to the actuation element,engages, the elongated hole being embodied in such a way that uponactuation of the actuation element within the first actuation range, thefurther pin is moved inside the elongated hole but without therebymoving the one pin, i.e. the first latching element. What is achievedthereby is that upon an actuation of the actuation element within thefirst actuation range, the first latching element is left in its initialposition or the latched connection to the second latching element isthus established.

In a particularly preferred embodiment the brake unit encompasses atleast one brake element that is biased with the aid of a further elasticelement into a braked position, which brake element contacts the shaftin the braked position and generates the braking force by way of thatcontact. The brake element is movable by manual actuation of theactuation element, against the return force of the further elasticelement, from the braked position into a released position. Couplingbetween the actuation element and the brake element is accomplished viaa coupling unit. In this released position, in particular, pivoting ofthe pivot unit around the longitudinal axis of the shaft is possible.

In a preferred embodiment the actuation element is coupled purelymechanically to the brake element with the aid of a coupling unit.Alternatively or additionally, a magnetic and/or electrical coupling isalso possible.

The advantage achieved thanks to the preferably purely mechanicalcoupling is that pivoting of the pivot unit is possible even without thedelivery of electrical current. The elastic element furthermore ensuresthat the brake unit always automatically immobilizes the pivot unit bythe fact that without actuation of the actuation element, the brakeelement is always arranged in the braked position and thus exerts thenecessary braking force. Inadvertent pivoting of the pivot unit thuscannot occur, so that property damage and personal harm are prevented.In addition, a purely mechanically coupled brake element of this kind,which produces its braking effect via contact with the shaft and thusvia the frictional force thereby created, allows the braking force to becapable of being steplessly regulated by the operator depending on howfar he or she in fact actuates the actuation element. This makespossible, in particular, precise adjustment of the position of the pivotunit. The actuation element is only minimally actuated for this, so thata braking force is still being exerted but it is only of such magnitudethat adjustment of the pivot unit is nevertheless possible; the entireweight of the pivot unit does not need to be held by the operator, thatweight instead being for the most part applied by the braking force. Theoperator can thus concentrate on the specific precise positioningoperation and can perform it substantially more accurately than if he orshe needed to hold the entire pivot unit.

The braking force is generated in particular by the frictionalconnection between the brake element and the shaft. The braking forcehere depends in particular on the force with which the brake element ispressed against the shaft. That force is in turn applied by the elasticelement; upon an actuation of the actuation element, a force directedagainst the return force of the elastic element is applied, therebydecreasing the resultant force acting on the shaft due to the brakeelement. so that a smaller braking force is also generated. This makespossible the above-described stepless regulation of the braking force.

In a particularly preferred embodiment of the invention, the brake unitencompasses several brake elements each biased into the braked positionby a respective elastic element. All the brake elements are coupled tothe actuation element in such a way that they are movable with the aidof the actuation element from the braked position into the releasedposition. The result of providing multiple brake elements, which inparticular are arranged at different points on the shaft, is that agreater, and in particular homogeneously distributed, braking force isachieved, so that braking and immobilization of the pivot unit can occurreliably and securely.

The brake elements are, in particular, embodied identically. The elasticelements as well are preferably embodied identically. Alternatively, inan embodiment, different brake elements and/or different elasticelements can also be used. In embodiments having multiple brake elementsthe features described below, with which the brake elements and elasticelements can be further developed, can be used both for all brakeelements and respectively only for some of the brake elements. Inparticular, different brake elements having some of the featuresdescribed below can be combined with one another.

The result of coupling all the brake elements to a single actuationelement is that the operator also correspondingly needs to actuate onlyone actuation element, and particularly simple operation is thusensured. The brake element or elements are embodied, in particular, asradial pistons, i.e. pistons that exert radially directed forces on theshaft when they are pressed against it. With radial pistons of thiskind, on the one hand a particularly simple configuration is achievedand on the other hand very good force transfer to the shaft is ensured.

The radial piston or pistons preferably each have a contact region,beveled at a predetermined angle, for contacting the shaft, the forcebeing applied by the radial piston in particular via that contactregion. With a beveled region, force transfer occurs in particular alonga line. The contact region is beveled preferably at an angle of between20° and 45°, in particular approximately 30°, relative to the envelopingsurface of the radial piston. It is correspondingly at, in particular,an angle of between 45° and 70°, preferably 60°, with respect to the endsurface.

In an alternative embodiment of the invention the contact region canalso have a different shape. In particular, the contact region can alsobe embodied in the shape of a cylinder segment and, in particular, canbe coordinated exactly with the diameter of the shaft, so that a verylarge contact region is achieved and force can be transferred not onlyalong a line but over a large area. Even more reliable and uniform forcetransfer, and a better braking and immobilization effect, are therebyachieved.

The elastic element or elements with which the brake elements are biasedinto the braked position are embodied in particular as springs,preferably as compression springs. A particularly simple and reliableconfiguration is thereby achieved. Alternatively, for example, rubberblocks can also be used.

In a particularly preferred embodiment the brake element is steplesslymovable from the braked position into the released position, so that adifferent braking force is respectively applied depending on theposition of the brake element. The result of this is that the brakingforce can be regulated steplessly, in particular continuously. Operatingconvenience is thereby enhanced, and intuitive operation is enabled.

The actuation element encompasses in particular a lever pivotable arounda pivot axis relative to a housing of the pivot unit. This lever is, inparticular, biased into a default position by the elastic element of thebrake unit and/or by further elastic elements, this default positionbeing that position in which the actuation element is not actuated, andwhich the actuation element thus assumes when the brake element orelements is or are arranged in the braked position.

It is particularly advantageous if the lever is pulled toward theoperator for release from said default position, thereby enablingparticularly simple and convenient operation.

In a particularly preferred embodiment the brake unit encompasses atleast two, preferably four brake elements embodied as radial pistons,each two of said radial pistons being arranged opposite one another withreference to a center plane of the shaft, these oppositely arrangedradial pistons each being biased in opposite directions, i.e. toward oneanother, by a respective elastic element. An even number of radialpistons, for example two, four, six, or eight radial pistons, isaccordingly preferred, two corresponding ones of the radial pistonsdescribed above respectively being arranged opposite one another.

A particularly simple and compact configuration is thereby achieved. Auniform application of force is moreover generated. The radial pistonsare in particular arranged and/or embodied in such a way that theirforce introduction points are distributed symmetrically over thecircumference of the shaft.

It is furthermore advantageous if a respective intermediate elementfixedly connected to the actuation element is arranged between the tworadial pistons biased toward one another, and if the two radial pistons,as a result of their biasing, press via a respective elastic elementagainst oppositely located sides of that intermediate element. Upon anactuation of the actuation element, the intermediate element becomestilted in such a way that the distance between the radial pistonsbecomes greater as a function of the actuation travel of the actuationelement, i.e. as a function of how far the actuation element is movedout of its default position, so that the radial pistons are moved fromthe braked position toward the released position. In particular, thetilting of the intermediate element causes it to become skewed, so thatit contacts the radial pistons with its edges and pushes them apart. Avery reliable, compact construction of simple configuration is therebyachieved. This construction furthermore makes it possible for theactuation element, as a result of this clamping of the intermediateelement (joined fixedly to the actuation element) between the two biasedradial pistons, to be automatically biased by the radial pistons intoits default position, so that separate elastic elements do not need tobe provided for this purpose.

The tilting of the intermediate element is accomplished in particulararound the same pivot axis as the pivoting of the lever upon actuationthereof. In particular, the intermediate elements, and the bearings withwhich the lever is mounted on the housing rotatably therearound, areembodied integrally, thereby achieving a particularly simpleconfiguration and reliable operation.

When the radial pistons are arranged in the braked position, their endfaces then contact the intermediate element, which is arranged at apredetermined angle relative to the horizontal. Upon tilting of theintermediate element, its surfaces likewise become correspondinglytilted, so that the angle with respect to the horizontal becomes greaterand, as a result, the distance between the radial pistons biased towardone another becomes greater. The increase in the distance in turndecreases the force with which the radial pistons are pressed againstthe shaft, so that the braking force becomes correspondingly reduced.

In a particularly preferred embodiment the actuation element is biased,via the elastic element with which the brake element is biased thebraked position, into a default position in which the actuation elementis arranged when the brake element is arranged in the braked position.Alternatively or additionally, the actuation element can also be biasedinto the default position via further, separate elastic elements, forexample springs.

In a particularly preferred embodiment the shaft is hollow. This has theadvantage that it can serve as a cable conduit through which wiring canbe provided between the stand base and the components arranged in thepivot unit. This has the advantage that even upon pivoting of the pivotunit, the wiring cannot be detached and is not in the way.

It is furthermore advantageous if the pivot unit encompasses a zoomsystem and/or an objective system having multiple objectives selectablyintroducible into the beam path. A different magnification of the objectcan be achieved depending on the objective.

The objectives are embodied in particular as parfocal objectives, whichhas the advantage that different objectives can be interchanged with nooccurrence of a focus shift, so that no readjustment by the operator isnecessary.

It is moreover particularly advantageous if the objectives arecoordinated at the factory with the predetermined distance between thelongitudinal axis of the shaft, i.e. the rotation axis of the pivotunit, and the position in which the respectively selected object isarranged when it is used, i.e. the operating position. The result ofthis coordination of the objectives with the rotation axis of the pivotsystem is to implement eucentric pivoting of the pivot unit, so that theoperator does not need to carry out new adjustment operations uponpivoting of the pivot unit.

BRIEF DESCRIPTION OF THE DRAWING VIEWS

Further features and advantages of the invention are evident from thedescription that follows, which explains the invention in further detailwith reference to exemplifying embodiments in conjunction with theappended Figures, in which:

FIG. 1 is a schematic perspective depiction of a microscope;

FIG. 2 is a schematic perspective depiction of a portion of themicroscope, showing a brake unit;

FIG. 3 is a sectioned depiction of a portion of the microscope accordingto FIGS. 1 and 2, showing the brake unit arranged in a braked position;

FIG. 4 is a further sectioned depiction of a portion of the microscopeaccording to FIGS. 1 and 2, with a side view of the brake unit arrangedin the braked position;

FIG. 5 is a sectioned depiction of a portion of the microscope accordingto FIGS. 1 and 2, with a brake unit arranged in a released position;

FIG. 6 is a sectioned depiction of a portion of the microscope accordingto FIGS. 1 and 2, with a side view of the brake unit arranged in thereleased position;

FIG. 7 is a further schematic perspective depiction of a portion of themicroscope according to FIGS. 1 and 2, showing a click-stop mechanism;

FIG. 8 is a sectioned depiction of a portion of the microscope accordingto FIGS. 1 and 2, with a latching element of the click-stop mechanismarranged in an initial position;

FIG. 9 is a sectioned depiction of a portion of the microscope accordingto FIGS. 1 and 2, an actuation element having been actuated in a firstactuation range;

FIG. 10 is a sectioned depiction of a portion of the microscopeaccording to FIGS. 1 and 2, with an actuation element actuated within asecond actuation range;

FIG. 11 is a schematic perspective depiction of the microscope accordingto FIGS. 1 and 2, showing a rear side of the microscope with housingparts omitted;

FIG. 12 is a sectioned depiction of the microscope according to FIGS. 1and 2, the pivot unit being arranged in a zero position;

FIG. 13 is a further sectioned depiction of the microscope according toFIGS. 1 and 2, the pivot unit being pivoted out of the zero positioninto a first position;

FIG. 14 is a further sectioned depiction of the microscope according toFIGS. 1 and 2, the pivot unit being moved out of the zero position intoa second position;

FIG. 15 is a diagram of the forces acting as a function of the pivotangle of the pivot unit, according to a first embodiment;

FIG. 16 is a diagram of the forces acting as a function of the pivotangle of the pivot unit, according to a second embodiment;

FIG. 17 is a diagram of the forces acting as a function of the pivotangle of the pivot unit, according to a third embodiment; and

FIG. 18 is a diagram of the forces acting as a function of the pivotangle of the pivot unit, according to a fourth embodiment.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic perspective depiction of a digital microscope 10.Microscope 10 encompasses a stationary stand body 12 with whichmicroscope 10 can be placed on a surface.

Microscope 10 furthermore has a pivot unit 14 pivotable relative to saidstand body 12. The pivotable fastening is also described in furtherdetail below in conjunction with FIG. 2.

Pivot unit 14 encompasses at least an image sensing unit with which animage of the objects to be examined microscopically can be acquired. Inparticular, using this image sensing unit it is possible to acquire notonly individual images but also videos, which allow observation fromdifferent viewing angles of the object to be examined microscopically.

Pivot unit 14 furthermore comprises an objective system and/or a zoomsystem with which different magnifications of the objects to be examinedmicroscopically can be set. The objective system has, in particular, aplurality of objectives, one of which can respectively be swungselectably into the beam path of microscope 10 so that said swung-inobjective is currently being used. The beam path or optical axis ofmicroscope 10 is labeled in FIG. 1 with the reference character 15.

The image sensing unit, which is in particular at least one camera, andthe objective system, are not visible in FIG. 1 because they areconcealed by a housing 16 of pivot unit 14.

The objectives of the objective system are, in particular, embodied tobe parfocal, so that an objective change does not necessitate refocusingby the operator. The objectives are, in particular, coordinated with thedistance between the rotation axis around which pivot unit 14 is rotatedand the interface of the objectives, i.e. the region in which theobjectives are arranged; this yields a eucentric system, the consequencebeing that refocusing need not occur when pivot unit 14 is pivotedrelative to stand body 12.

Also fastened on stand body 12 is a stage 18 on which the objects to beexamined microscopically are placed. This microscope stage 18 can bedisplaced in the direction of double arrow P1 relative to stand base 12with the aid of adjusting wheels 20, thereby enabling focusing of theobjects to be examined microscopically.

FIG. 2 is a schematic perspective depiction of a portion of microscope12, looking toward a brake unit 22 and showing the mounting of pivotunit 14 relative to stand body 12. Housing 16 of pivot unit 14 is, forthis purpose, omitted. The upper part of pivot unit 14 is also notdepicted, so that these internally located components can be made morevisible.

Stand body 12 encompasses a shaft 24 on which pivot unit 14 is mountedrotatably around longitudinal axis 26 of shaft 24. Longitudinal axis 26of shaft 24 thus constitutes the rotation axis of pivot unit 14.

Pivot unit 14 encompasses a rod 28 that is fastened fixedly on pivotunit 14 and is guided within a gate 30 of stand body 12. Gate 30 isembodied, in particular, in the shape of a circular segment or arc, thecenter point of that circle being located on longitudinal axis 26. Gate30 and the engaging rod 28 result on the one hand in movement guidanceand on the other hand, in particular, in a limitation of the maximumpossible pivoting.

Gate 30 is embodied in particular in such a way that it covers an angleof 120°, with the consequence that the pivot unit is pivotable, from azero position shown in FIGS. 1 and 2, through 60° in both directions ofdouble arrow P2. The zero position is that position at which the pivotis oriented uprightly, i.e. it is arranged centeredly above microscopestage 18, and the lateral housing parts of housing 16 are alignedvertically. In other words, the zero position is that position in whichoptical axis 15 of microscope 10 extends perpendicularly to the surfaceof microscope stage 18.

Brake unit 22, which comprises a total of four radial pistons 32 to 38,is provided in order to immobilize pivot unit 14 in a desired positionand in order to brake its motion; said pistons are each biased via aspring 40 in such a way that they press against the surface of shaft 24so that a frictional connection is formed, the force resulting therefromserving respectively as a braking force or immobilizing force. FIGS. 3and 4 are respective sectioned depictions of the portion of pivot unit14 and of shaft 24, FIG. 3 being a plan view and FIG. 4 a side view.What is depicted in both Figures is a braked position in which radialpistons 32 to 38 are contacting the surface of shaft 24, and pivot unit14 is thus immobilized.

Radial pistons 32 to 38 each comprise a beveled contact surface 42, thelatter enclosing in particular an angle of between 45° and 70°,preferably an angle of approximately 60°, with end face 32 a to 38 a ofthe respective radial piston. The result of these beveled surfaces isthat the radial pistons contact shaft 24 along the largest possiblecontact line, and exert on the shaft a force F1 by means of which thenecessary friction is applied and thus immobilization of brake unit 22is accomplished.

In an alternative embodiment more or fewer than four radial pistons 32to 38, for example two radial pistons or six radial pistons, can also beprovided. Contact surface 42 can moreover also have a different shape.For example, the shape of the contact surface can be adapted to that ofshaft 24, so that force transfer is accomplished not only along a line,but in planar fashion.

Brake elements other than radial pistons 32 to 38 can moreover also beused, for example brake shoes.

In addition, other elastic elements, for example rubber or siliconeblocks, can also be used instead of springs 40.

Brake unit 22 can be released with the aid of an actuation element 44.This actuation element 44 encompasses a lever 46 whose end facing awayfrom brake unit 22 can be manually actuated by an operator. In a defaultposition, for example as shown in FIGS. 1 and 2, this actuation element44 is not actuated. In order to release brake unit 22, lever 46 must bemoved by the operator out of said default position. In the exemplifyingembodiment shown in FIGS. 1 and 2, lever 46 must be pulled by theoperator toward him- or herself, so that simple operation is possible.

Actuation element 44 furthermore encompasses two intermediate elements48, 50 by way of which lever 46 is mounted pivotably around a pivot axis52 relative to housing 16. These intermediate elements 48, 50furthermore comprise extensions 54, 56 that are each arranged betweentwo mutually oppositely arranged radial pistons 32 to 38. In the brakedposition, the surfaces of these extensions 54, 56 and the end faces ofradial pistons 32 to 38 are aligned approximately parallel to oneanother.

When lever 46 is moved from the operating position toward oneself, i.e.in the direction of arrow P3 (FIG. 6), intermediate elements 48, 50 arethen pivoted together with lever 46, with the consequence thatextensions 54, 56 become tilted, the result being that, as shown in thesectioned depictions of FIGS. 5 and 6, radial pistons 52 to 58 are movedout of the braked position, away from one another, toward a releasedposition. In the released position shown in FIGS. 5 and 6, radialpistons 52 to 58 are moved sufficiently far away from one another thatthey no longer contact shaft 24 at all, so that no further braking forceat all exists. Conversely, if lever 46 is not moved quite so far as inthe case of the extreme situation in FIGS. 5 and 6, it may then be thecase that radial pistons 32 to 38 are still in contact with shaft 24,but the force is less than in the braked position. Pivot unit 14 canthus be moved despite the braking force, but the braking force can thusbe adjusted steplessly by the operator depending on how far he or shepulls lever 46. Precise positioning of the pivot units, in particular,is thus easily possible.

When the operator releases lever 46, however, radial pistons 32 to 38are automatically moved back into the braked position by springs 40, sothat brake unit 22 is automatically immobilized and inadvertentuncontrolled pivoting of pivot unit 14 is avoided.

A further effect of springs 40 of radial pistons 32 to 38, via thecontact of radial pistons 32 to 38 with intermediate elements 48, 50, isthat when lever 46 is released, it is automatically moved back into thedefault position without requiring further elastic elements for thatpurpose. Alternatively, however, further elastic elements for biasinglever 46 into the default position can also be provided.

FIG. 7 is a further schematic perspective depiction of the portion ofmicroscope 10, here looking toward a latched connection serving as a“click-stop” mechanism. This latched connection is established between afirst latching element embodied as pin 60 and a second latching elementembodied as recess 62. Pin 60 is part of pivot unit 14, whereas recess62 is provided in a ring 64 of stand body 12.

FIGS. 8 to 10 are respective sectioned depictions of a portion ofmicroscope 10 showing said click-stop mechanism, the section beingselected so that pin 60 is sectioned. FIGS. 8 to 10 depict differentpositions of pin 60 that result as a function of the actuation ofactuation element 44.

FIG. 8 depicts the state in which brake unit 22 is arranged in thebraked position and lever 46 is thus unactuated and arranged in itsdefault position. Pin 60 is biased into the initial position via anelastic element embodied as spring 66. When pivot unit 14 is arranged inits zero position, pin 60 that is arranged in the initial positionengages into recess 62 so that a latched connection is established.Because brake unit 22 is arranged in the braked position when lever 46is arranged in the default position, pivoting of pivot unit 14 isgenerally not possible.

Lever 46 is connected via a connecting pin 68 to pin 60, said connectingpin 68 projecting into an elongated hole 70 of pin 60.

When lever 46 is actuated out of the default position within apredetermined first actuation range, connecting pin 68 is then movedaway from stand body 12 only sufficiently far that it is moved withinelongated hole 70, but without moving pin 60 out of its initialposition. This first actuation range corresponds approximately to halfthe maximum possible actuation travel of lever 46.

When lever 46 is actuated within this first actuation element, brakeunit 22 is released at least sufficiently that it is possible for pivotunit 14 to pivot. When pivot unit 14 is moved out of the zero position,pin 60 is then moved out of its initial position via contact with ring64 out of the initial position, and correspondingly slides on ring 64.In order to ensure this movement out of recess 62, recess 62 has, inparticular, beveled edges and the pin has, in particular, asemi-spherical end 72 that engages into recess 62.

When pivot unit 14 is moved back into the zero position while lever 46is still actuated within the first actuation range, pin 60 isautomatically moved back into the initial position due to the returnforce of spring 66 when the zero position is reached and thus whenrecess 62 is reached, and thus latches into recess 62. The operator canperceive this latching-in haptically by way of corresponding vibrationsand/or acoustically by way of a corresponding “click,” so that theoperator can return exactly to the zero position at any time.

If, however, the operator actuates lever 46 farther than the firstactuation range, so that it is actuated within a predetermined secondactuation range as depicted, for example, in FIG. 10, pin 60 is then,via contact with connecting pin 68, already moved against the returnforce of spring 66 sufficiently far out of the initial position thateven when pivot unit 14 is arranged in the zero position, pin 60 doesnot latch into recess 62. This has the advantage that pivot unit 14 canbe moved through the zero position while no corresponding latching-inoccurs. This avoids vibration, for example, which is advantageous whenacquiring videos during pivoting of pivot unit 14.

FIG. 11 is a further schematic perspective depiction of microscope 10looking toward its rear side, a rear wall of the housing of stand body12 being omitted in order to make the internally located componentsvisible.

Arranged inside the housing of stand body 12 is a stub shaft 80 that isarranged, in particular, coaxially with shaft 24. In an alternativeembodiment, stub shaft 80 and shaft 24 can also be embodied integrally.

A torsion spring 82 is mounted on this stub shaft 80 in such a way thatits turns extend around stub shaft 80, so that the axis of torsionspring 82 is also arranged coaxially with stub shaft 80 and thus withshaft 24, and thus in turn with rotation axis 26 of pivot unit 14.

The two ends 84, 86 of the wire of torsion spring 82 are bent upward andare arranged in such a way that a gap 88 is embodied between them. Thatend of rod 28 which faces away from pivot unit 14 projects into this gap88. Also arranged in this gap 88 is a projection 90 connected fixedly tostand body 12.

FIGS. 12 to 14 are respective sectioned depictions of microscope 10, thesection being placed so that the front end 86, viewed from the rearside, is sectioned. In FIG. 12, pivot unit 14 is arranged in the zeroposition. In this zero position, rod 90 does not contact either of thetwo spring ends 84, 86 and torsion spring 82 is not loaded, so that noforce and no moment are exerted by it on pivot unit 14.

If the weight of pivot unit 14 is regarded as a concentrated force Gthat acts at the center of gravity S of pivot unit 14, then in the zeroposition the vertical of that force G, called the “gravity vertical”100, extends through rotation axis 26 of pivot unit 14, so that notorque around rotation axis 26 is generated by weight G.

In FIG. 13, pivot unit 14 is pivoted out of the zero positionapproximately 60° to the left in a first direction. Torsion spring 82braces with its second end 86 against projection 90, the other end 84 ofthe torsion spring being concurrently moved via rod 28, so that torsionspring 82 becomes loaded and exerts a return force F_(F) on rod 28 andthus on pivot unit 14.

When pivot unit 14 is pivoted out of the zero position, gravity vertical100 is then no longer directed so that it intersects rotation axis 26.The weight G can instead, in accordance with a parallelogram of forces,be divided into a radial force F_(R) and a tangential force F_(T). Thisradial force F_(R) is directed toward rotation axis 26, so that itgenerates no torque around rotation axis 26. The tangential force F_(T),on the other hand, generates a corresponding torque (tangential moment)M_(T) around rotation axis 26, by which pivot unit 14 is pulleddownward.

The return force F_(F) of the spring is directed oppositely to thetangential force F_(T) and parallel to it, so that it likewise generatesa torque, called the “return moment” M_(R), around rotation axis 26,although it is directed oppositely to the tangential moment M_(T) and isthus referred to as a “counter-moment.” The moment resulting from thetorque M_(T) generated by the tangential force F_(T), and from thecounter-moment, is thus less than the tangential moment M_(T) generatedby the tangential force F_(T). The consequence of this is that anoperator needs to apply less force in order to move pivot unit 14 towardthe zero position. The dimensions of brake unit 22 can furthermore besmaller, since in order to immobilize pivot unit 14 in a desiredposition it thus needs to apply only a smaller braking force,specifically one that only needs to compensate for the resultant moment.

FIG. 14 shows the pivoting of pivot unit 14 in the direction opposite tothe deflection as seen in FIG. 13. In this case first end 84 of thespring braces against projection 90, whereas second end 86 of the springis entrained by rod 28. Thanks to the symmetrical embodiment of torsionspring 82 and the symmetrical arrangement, once again a return momentM_(RF) is generated which is directed oppositely to the tangentialmoment M_(T) of pivot unit 14 and has the same magnitude as in the caseof the same deflection in the other direction. By way of the strength oftorsion spring 82 that is used, it is possible to adjust the magnitudeof the return force and thus of the return moment M_(R), and thus themagnitude of the residual resultant moment

In a first embodiment shown in FIG. 15, torsion spring 82 is selected insuch a way that the return moment M_(R) for a pivoting motion of 50° outof the zero position is of approximately the same magnitude as thetangential moment M_(T), so that no resultant moment remains. Uponpivoting of more than 50° out of the zero position the return momentM_(R) is greater than the tangential moment M_(T), so that a negativeresultant moment is produced.

In a second embodiment shown in FIG. 16, torsion spring 82 is selectedin such a way that the return moment M_(R) for a pivoting motion of 38°out of the zero position is of approximately the same magnitude as thetangential moment M_(T), so that no resultant moment remains. Uponpivoting of more than 38° out of the zero position the return momentM_(R) is greater than the tangential moment M_(T), so that a negativeresultant moment is produced.

In a third embodiment shown in FIG. 17, torsion spring 82 is selected insuch a way that the return moment M_(R) is always greater than or equalto the tangential moment M_(T), so that the resultant moment is alwaysless than or equal to zero.

In a fourth embodiment shown in FIG. 18, torsion spring 82 is selectedin such a way that the return moment M_(R) is always less than thetangential moment M_(T) or equal to the tangential moment M_(T), so thatthe resultant moment is always greater than zero. With this embodiment,unlike with the other embodiments, pivot unit 16 is not prevented fromabutting against a stop in order to limit the maximum pivot angle ofpivot unit 16, but a result of this embodiment is also that the operatorneeds to exert less force for pivoting, and that the required brakingforce of brake unit 22 is smaller. In particular, upon pivoting throughthe maximum possible angle out of the zero position, the return momentM_(R) is of the same magnitude as the tangential moment M_(T).

In all the embodiments, the torsion spring is selected in such a waythat over the entire pivoting range, the return moment M_(R) correspondsto 0.8 times to 1.2 times the tangential moment M_(T). What is achievedthereby is that the resultant moment M_(R) is always equal to atmost+/−20% of the tangential moment M_(T), and thus the force to beapplied by the operator or by brake unit 22 is always small, and pivotunit 22 is thus prevented from springing away in both directions whenbrake unit 22 is released.

In an alternative embodiment of the invention, other types of springsand other elastic elements can also be used instead of torsion spring82.

PARTS LIST

10 Microscope

12 Stand body

14 Pivot unit

15 Optical axis

16 Housing

18 Microscope stage

20 Adjusting wheels

22 Brake unit

24 Shaft

26 Rotation axis

28 Rod

30 Gate

32 to 38 Radial piston

32 a to 38 a End surface

40 Spring

42 Contact surface

44 Actuation element

46 Lever

48, 50 Intermediate element

52 Pivot axis

54, 56 Extension

60 Pin

62 Recess

64 Ring

66 Spring

68 Connecting pin

70 Elongated hole

72 End

80 Stub shaft

82 Torsion spring

84, 86 End

88 Gap

90 Projection

100 Gravity vertical

F1, F_(F), F_(R), F_(T), G Force

M_(R), M_(T) Moment

S Center of gravity

P1 to P3 Direction

What is claimed is:
 1. A digital microscope comprising: a stationarystand body including a shaft having a longitudinal axis; a pivot unitmounted on the shaft of the stand body pivotably about the longitudinalaxis of the shaft, wherein the pivot unit includes an image sensing unitfor acquiring images of objects to be examined microscopically; a brakeunit for braking and/or immobilizing the pivot unit; an actuationelement for releasing the brake unit; at least one elastic elementarranged to exert, upon pivoting of the pivot unit out of apredetermined zero position, a return moment on the pivot unit, thereturn moment being directed against a tangential moment generated by aweight of the pivot unit; wherein the following equation is satisfied atleast in a portion of a pivoting range of the pivot unit:M_(R)>=M_(T) M_(R)=return moment of the elastic element M_(T)=tangentialmoment of a weight of the pivot unit.
 2. The microscope according toclaim 1, wherein at least in a portion of a pivoting range of the pivotunit, the return moment corresponds to 0.8 to 1.2 times the tangentialmoment.
 3. The microscope according to claim 1, wherein the equation issatisfied for any pivoting of the pivot unit out of the zero positionthrough at least 50% of a maximum pivot angle of the pivot unit from thezero position.
 4. The microscope according to claim 1, wherein theequation is satisfied for the entire pivoting range.
 5. The microscopeaccording to claim 1, wherein the elastic element is fastened on thestand body.
 6. The microscope according to claim 1, wherein the elasticelement is a torsion spring.
 7. The microscope according to claim 6,wherein the stand body includes a gate, and a rod that projects into thegate is fixedly arranged on the pivot unit.
 8. The microscope accordingto claim 7, wherein the gate is in the shape of a circular segment orarc having a center point located on the rotational axis of the pivotunit.
 9. The microscope according to claim 7, wherein the torsion springis arranged rotatably on a stub shaft, the torsion spring includes afirst end and a second end each angled with respect to turns of thetorsion spring such that a gap is defined between the first and secondends, the rod projects into the gap, and a projection of the stand bodyprojects into the gap.
 10. The microscope according to claim 9, whereinupon pivoting of the pivot unit out of the zero position in a firstdirection, the first end of the torsion spring braces against theprojection and the second end of the torsion spring is entrained by therod; and upon pivoting of the pivot unit out of the zero position in asecond direction opposite to the first direction, the second end of thetorsion spring braces against the projection and the first end of thetorsion spring is entrained by the rod.
 11. The microscope according toclaim 10, wherein when the pivot unit is in the zero position, the roddoes not contact either of the first and second ends of the torsionspring.
 12. The microscope according to claim 1, wherein the elasticelement is unloaded when the pivot unit is in the zero position.
 13. Themicroscope according to claim 1, wherein the pivot unit includes a firstlatching element and the stand body includes a second latching elementcomplementary to the first latching element, wherein the first latchingelement and the second latching element are coupled to one another whenthe pivot unit is arranged in the zero position and the actuationelement is arranged in an unactuated default position, and wherein thefirst latching element and the second latching element are coupled toone another when the pivot unit is arranged in the zero position and theactuation element is actuated within a predetermined first actuationrange.
 14. The microscope according to claim 1, wherein the brake unitincludes a brake element biased by a further elastic element into abraked position in which the brake element contacts the shaft, whereinthe brake element is movable against a return force of the furtherelastic element from the braked position into a released position bymanual actuation of the actuation element, and wherein the actuationunit is coupled to the brake element.